Spekulatius (Dutch Spice Cookies)
Beat the butter, sugar and egg for about 10 minutes, until light and fluffy. Stir in the flour, ground almonds, baking powder, spices and lemon zest and mix until a smooth dough is formed. Wrap with plastic wrap and refrigerate for about 1 hour.
Roll the dough out onto a floured surface until about 4 mm (approximately 1/8 inch) thick. Cut into the rectangles the same size as the spekulatius mold and press each rectangle into the mold. Dust the mold with flour between each rectangle to prevent sticking. Place the pressed dough onto a baking sheet lined with parchment paper and sprinkle with the almond slivers. Bake in an oven preheated to 200°C (approximately 400°F) for 20 minutes, until golden brown. Remove from the oven and cool on a wire rack.